JP2510608B2 - Electrostatic coating equipment - Google Patents

Description

The present invention relates to a rotary cup type electrostatic coating device.

[Prior Art] In a rotary cup type electrostatic coating device, the rotary cup is formed such that its inner peripheral surface is tapered toward the front side and is supplied to the inner periphery of the rotary cup. The coating material is made into a thin film having a uniform thickness by the centrifugal force caused by the rotation of the rotary cup, and is sent to the knife edge portion at the tip of the rotary cup, and atomized and discharged from the knife edge portion. Here, a high voltage is applied between the rotary cup and the object to be coated, and the paint is electrostatically atomized and flies to the side of the object to be coated and adheres to the object to be coated.

However, since the rotary cup is driven to rotate at a high speed, the atomized paint that is atomized and released from the knife edge may be scattered outward by centrifugal force and may not be able to fly to the side of the object to be coated. Therefore, the yield of the paint is greatly reduced. Therefore, conventionally, an air jet is formed on the outer edge of the knife edge so as to surround the knife edge over the entire circumference, and compressed air is ejected from the air jet to surround the paint with air. It is designed to prevent the paint from splashing.

[Problems to be Solved by the Invention] However, in this case, when a part of the air ejection port is clogged and the ejection amount of the ejection air is reduced, the coating of the paint by the air becomes insufficient immediately, There is a problem that the yield of the paint may decrease. Also, if the rotating speed of the rotating cup drops rapidly for some reason, the effect of the centrifugal force on the paint supplied to the inner peripheral surface of the rotating cup becomes insufficient, and the paint becomes evenly thin on the knife edge. There was also a problem that the paint could not be atomized as uniform and small particles without being sent.

The present invention has been made in view of the above points, and it is possible to prevent the coating of air from being insufficiently surrounded by the air and to prevent the rotation speed of the rotating cup from decreasing. It is intended.

[Means for Solving the Problems] In the present invention, the coating material, which is formed by expanding the inner peripheral surface in a tapered shape toward the front and is supplied to the inner peripheral surface, is sent forward in a thin film shape as the coating material rotates. In an electrostatic coating apparatus having a rotary cup 1 for electrostatically atomizing paint from a knife edge portion 2 at the tip of the rotary cup 1, an air jet port 3 for jetting air forward to the outer peripheral portion of the knife edge portion 2 of the rotary cup 1. Is formed, and a large number of blades 4, 4 ... Are provided around the outer circumference of the rotating cup 1 at the rear portion of the air ejection port 3 and air is blown from the rear side of the blade 4 to the rotating cup 1 on the blade 4. Air blowing means 5 for applying a force in the direction of rotation and for allowing the air passing through the blades 4 to reach the outer peripheral portion of the knife edge portion 2.
Is provided on the outer peripheral portion of the rotary cup 1.

[Operation] By blowing air to the blades 4 provided on the outer periphery of the rotary cup 1, the air surrounding the paint can be assisted by this air, and the rotation force applied to the blades 4 can rotate the rotary cup 1. Can be assisted,
It is possible to prevent the coating of air from being insufficiently surrounded by air and the rotation speed of the rotating cup 1 from decreasing.

[Examples] The present invention will be described in detail below with reference to Examples. The rotating cup 1 is formed by the inner cylinder 8 and the outer cylinder 9 as shown in FIG. 1. The outer cylinder 9 is fitted on the outer periphery of the inner cylinder 8 to fix the fixing ring 10 to the outer cylinder 9 at the rear side. The outer cylinder 9 is fixed to the inner cylinder 8 by being screwed onto the outer circumference of the inner cylinder 8. The inner cylinder 8 is formed of a front cylinder portion 11, a rear cylinder 12, and a rotary shaft portion 13, and the rotary shaft portion 13 extends rearward from a wall 14 that partitions the front cylinder portion 11 and the rear cylinder portion 12. It is projected. Front cylinder
The inner peripheral surface of 11 is formed into a tapered surface whose diameter increases toward the front, and the inner peripheral surface of the rear tubular portion 12 is also formed into a tapered surface whose diameter increases toward the front. The tip of the front cylindrical portion 11 is formed as a knife edge portion 2 having a sharp tip over the entire circumference. The rotary shaft portion 13 is formed of a hollow cylinder having a flow passage 15 at the center thereof and is opened rearward. A plurality of ventilation passages 16, 16 ... Radially provided inside the wall 14 are provided in the flow passage 15. The flow path 15 is communicated with the front end portion, and the flow path 15 is opened to the outer peripheral surface of the inner cylinder 8 through the ventilation path 16. By attaching the outer cylinder 9 to the outer circumference of the inner cylinder 8, the ventilation passage 16 is opened in the space 17 formed between the outer cylinder 9 and the inner cylinder 8.
The space 17 is formed in front of the rotary cup 1 by the air ejection port 3 formed in the shape of a narrow slit over the entire circumference between the front end of the outer cylinder 9 and the vicinity of the rear edge of the knife edge portion 2 of the inner cylinder 8. It is open toward you. Further, tunnel portions 18 are formed at a plurality of locations on the peripheral portion of the wall 14 of the inner cylinder 8, and the front cylinder portion 11 and the rear cylinder portion 12 are connected to each other through the tunnel portions 18. Further, on the outer peripheral surface of the rear portion of the outer cylinder 9, a large number of blades 4, 4, ... Are provided so as to project at regular intervals over the entire circumference, as shown in FIG. A ring-shaped straightening plate 19 is attached. Each of the blades 4 is formed into a fan blade shape that gives a rotational force to the rotary cup 1 by the action of air from the rear.

The rotary cup 1 formed as described above is attached as shown in FIG. 3 by screwing the threaded portion 20 at the rear end of the rotary shaft portion 13 onto the tip of the relay pipe shaft 21. Is driven to rotate by an air motor 22 which is operated by receiving the supply of compressed air. The air motor 22 has a compressed air supply device such as a compressor.
23 is connected by piping, and a pressure air supply device 23 is also connected by piping to a bearing tube 24 that supports the relay pipe shaft 21, and compressed air is transferred from the bearing tube 24 through the relay pipe shaft 21 to the rotary shaft portion 13. It is supplied to the flow path 15 of. An air branch pipe 25 is provided on the outer peripheral portion of the bearing cylinder 24 so as to project outward, and an air nozzle 26 is projected forward from the air branch pipe 25. The air spraying means 5 is formed by the air branch pipe 25 and the air nozzle 26. The air nozzle 26 faces the vicinity of the rear side of the blade 4, and the compressed air is received from the bearing cylinder 24 through the air branch pipe 25. Are discharged from the air nozzle 26. A plurality of air blowing means 5 are provided so that the air nozzles 26 are arranged on the outer peripheral portion of the rotary cup 1 at a plurality of positions at equal intervals.
Further, the tip of a paint supply pipe 28 guided from a paint supply device 27 formed by a paint pump, a paint tank, etc. is inserted into the rear cylinder part 12 of the rear part of the inner cylinder 8 of the rotary cup 1, and further high voltage is applied. Connect the lead wire 30 of the generator 29 to the terminal of the bearing tube 24.
The rotary cup 1 is connected to 31 to be charged to a negative high potential, and a high potential difference is given to the grounded object 32 to be coated.

In the electrostatic coating apparatus formed as described above, the rotary cup 1 is rotated by the rotational driving of the relay pipe shaft 21 by the air motor 22 and the coating material is supplied from the coating material supply pipe 28 to the inner cylinder 8 of the rotating cup 1. Then, the paint moves forward along the tapered surface of the inner cylinder of the rear cylinder part 12 of the inner cylinder 8 and moves from the tunnel part 18 to the inner peripheral surface of the front cylinder part 11, and the centrifugal force generated by the rotation of the rotary cup 1 is applied. Then, the paint reaches the knife edge portion 2 at the tip of the inner cylinder 8 while spreading uniformly and thinly in a thin film, and the paint is discharged from the knife edge portion 2 in a negatively charged atomized state, and is electrostatically acted on the object to be coated. It can adhere to 32 and form a coating film on the surface. On the other hand, the compressed air supplied to the flow path 15 of the rotating shaft portion 13 passes through the ventilation path 16 and is vacant.
It reaches the inside of 15 and is discharged forward from the air jet port 3 over the entire circumference of the trailing edge portion of the knife edge portion 2. In this way, the air discharged from the air ejection port 3 becomes a shaving air which becomes a vortex along with the rotation of the rotary cup 1, and the paint discharged from the knife edge portion 2 is surrounded by this shaving air to make the rotary cup 1 It controls the scattering of the paint by the centrifugal force caused by the rotation of.

Further, when the compressed air discharged from the air nozzle 26 of the air blowing unit 5 is blown to the blade 4, a rotational force acts on the rotary cup 1 to assist the rotation of the rotary cup 1 and also to pass the blade 4. The generated air is blown toward the knife edge portion 2, so that the scattering of the paint can be regulated even with this air, and the scattering of the paint due to the centrifugal force is assisted. Here, the air blown to the blade 4 flows toward the knife edge portion 2 side in a state of being expanded along the outer periphery of the rotary cup 1 by the circumferential movement of the blade 4 as the rotary cup 1 rotates. It is possible to uniformly apply the air discharged from the air blowing means 5 to the entire circumference of the knife edge portion 2 without providing a large number of air blowing means 5. Further, the flow straightening plate 19 provided between the tips of the blades 4 restricts outward diffusion of the air blown to the blades 4 so that the air passing through the blades 4 can efficiently act on the knife edge portion 2. is there. As described above, by blowing air to the blades 4 of the rotary cup 1 to assist the rotation of the rotary cup 1, the rotational speed of the rotary cup 1 is significantly reduced even if the air motor 22 or the like malfunctions. The effect of the centrifugal force on the paint supplied to the inner peripheral surface of the rotating cup 1 is insufficient, and the paint is not sent to the knife edge portion with a uniform thinness, so that the paint is distributed as uniform and small particles. It is possible to prevent the atomization from becoming impossible and reduce the occurrence of coating failure. Further, even if the air is insufficiently ejected from the air ejection port 3 such as when the air ejection port 3 is partially clogged with the paint, the air passing through the blades 4 assists in controlling the scattering of the paint. In addition, it is possible to prevent the paint from being scattered by the centrifugal force of the rotating cup 1 and greatly reducing the yield.

[Effects of the Invention] As described above, in the present invention, a large number of blades are provided on the outer circumference of the rotary cup over the entire circumference, and air is blown from behind to the blades to rotate the rotary cups. In addition, since air blowing means is provided on the outer peripheral portion of the rotary cup that imparts air passing through the blade to the outer peripheral portion of the knife edge portion, it is possible to assist the rotation of the rotary cup by the action of air on the blade. , It is possible to prevent the rotational speed of the rotary cup from significantly decreasing even if the rotary drive force of the rotary cup decreases due to some reason, and it also helps to control the scattering of paint by the air passing through the blades. Therefore, even if the ejection of air from the air ejection port becomes insufficient, it is possible to prevent the regulation of the scattering of the paint from being greatly reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a rotary cup according to an embodiment of the present invention, and FIG.
FIG. 3 is a front view of the above rotary cup, and FIG. 3 is a schematic reduced view showing the entire embodiment of the above. Reference numeral 1 is a rotary cup, 2 is a knife edge portion, 3 is an air ejection port, 4 is a blade, and 5 is an air blowing means.

Claims (1)

(57) [Claims] 1. A paint, which is formed by expanding the inner peripheral surface in a tapered shape toward the front and is supplied to the inner peripheral surface, is sent to the front in a thin film in accordance with the rotation so that the paint is applied from a knife edge portion at the tip. In an electrostatic coating device equipped with a rotary cup for electrostatic atomization, an air jet port for jetting air forward is formed on the outer peripheral portion of the knife edge portion of the rotary cup, and the rotary cup of the rotary cup is formed behind the air jet port. A large number of blades are provided all around the outer circumference, and air is blown from the rear toward the blades to give a force to the blades in the direction to rotate the rotary cup, and at the same time the air that has passed through the blades reaches the outer peripheral portion of the knife edge. An electrostatic coating device characterized in that air blowing means is provided on the outer peripheral portion of a rotary cup.